98 CORVID.E. 



Books attempt to build their nest in a tree that was pre- 

 viously unoccupied by a nest, and at a distance from the 

 main body, the other Rooks invariably destroy the nest. 

 The reason for this is not very obvious, unless intended as 

 a punishment to the separatists for their want of sociability. 

 The Book lays four or five eggs, of a pale greenish ground 

 colour, blotched over with dark greenish brown ; the length 

 one inch eight lines, by one inch two lines in breadth. 



During the period of incubation, the male feeds the 

 female constantly, and occasionally takes her place upon 

 the eggs. Both birds labour incessantly to support their 

 young when hatched, and may be seen, early and late, 

 collecting food for them in the various modes already de- 

 scribed, the dilatable skin under the tongue distended with 

 a conspicuous mass, which is thus softened, and rendered 

 suitable to young and delicate organs. The young Books 

 are able to fly by the end of May, or the beginning of 

 June, and follow their parents to grass-fields, where they 

 are still fed for a time, but soon learn to select and obtain 

 sufficient for their own subsistence. The nest trees are in 

 some cases deserted from this time, and all the inhabitants 

 of the rookery roost together in some neighbouring wood, 

 from whence at an early hour they repair in flocks to their 

 feeding-ground, returning together with slow and measured 

 flight in the evening. Whenever the main body are feed- 

 ing, or otherwise engaged on the ground, two or three in- 

 dividuals are generally seen posted, like sentinels, in trees 

 close by, whose note of caution or alarm appears to be per- 

 fectly understood by the rest, and surprise or danger avoid- 

 ed apparently by a concerted understanding among them. 



Besides the general hatch which takes place in April, a 

 few young broods are produced late in the autumn. Gil- 

 bert White of Selborne, in his unpublished MSS. referred 



